The present invention relates generally to pixel array technology. More particularly, the present invention relates to vertical photo-detectors that include enhanced color sensitivity and a video interface that is compatible with conventional video systems.
Imaging sensors are commonly used in various applications such as digital cameras. The imaging sensor includes multiple pixel sensors that are arranged in an array. Light is reflected from a scene and received by the imaging sensor. The imaging sensor provides signal outputs that have magnitudes that correspond to the light intensity level for each pixel sensor within the array.
Conventional color imaging sensors include three sensor elements that are arranged as a cell within the array. Each cell thus includes a first sensor element that provides a red signal, a second sensor element that provides a green signal, and a third sensor element that provides a blue signal. Each of the sensor elements includes a color filter that is located above the surface of the device. For example, a red filter is placed above the first sensor element, a green filter is placed above the second sensor element, and a blue filter is placed above the third sensor element. The filters mask other colors so that the signal from each of the sensor elements corresponds to the detected color signals from the imaging sensor.
An improved vertical photo-detector cell has increased sensitivity when compared to a conventional photo-detector cell. The improved vertical photo-detector cell is configured to collect photo-carriers from adjacent improved vertical photo-detector cells to increase the effective area of the sensor region associated with each color.
According to an example of the present invention, a pixel cell for an imaging sensor includes a first and second improved vertical photo-detector cell. The first improved vertical photo-detector cell is located about a first location in the imaging sensor. The second improved vertical photo-detector cell is located about a second location in the imaging sensor. The second location is adjacent to the first location. A first photo-detector region is located in the first and second improved vertical photo-detector cells, and is arranged to detect light that substantially corresponds to a first color. The first photo-detector region has a first geometric center at the first location. A second photo-detector region is located in the second improved vertical photo-detector cell, and is arranged to detect light that substantially corresponds to a second color. The second photo-detector region has a second geometric center at the second location.
According to a further aspect of the present invention, the first color may correspond to one of red, green, and blue, and the second color may correspond to another of red, green, and blue.
According to another aspect of the present invention, the first photo-detector region is located in a first plane and the second photo-detector region is located in a second plane that is different from the first plane. The first plane in the photo-detector region is non-intersecting with respect to the second photo-detector region. According to one example, the first plane may be located above the second plane such that the first photo-detector region is closer to a surface of the imaging sensor. The first photo-detector region may be arranged to supply a signal via an electrical contact that extends from the first photo-detector region to the surface of the imaging sensor. According to another example, the first plane is located below the second plane such that the second photo-detector region is closer to a surface of the imaging sensor. The first photo-detector region may be arranged to supply a signal via an electrical contact that extends from the first photo-detector region to the surface of the imaging sensor without contacting the second photo-detector region.
In another example of the present invention, a third improved vertical photo-detector cell is located at a third location in the imaging sensor. The third location is adjacent to the first and second locations. A third photo-detector region is located in the third improved vertical photo-detector cell. The third photo-detector region is arranged to detect light that substantially corresponds to a third color. The third photo-detector region has a third geometric center at the third location. The pixel cell may also include a fourth improved vertical photo-detector cell that is located at a fourth location in the imaging sensor. The fourth location is adjacent to the first, second, and third locations. A fourth photo-detector region that is located in the fourth improved vertical photo-detector cell. The third photo-detector region is arranged to detect light that substantially corresponds to the third color. The fourth photo-detector region has a fourth geometric center at the fourth location. The first, second, third, and fourth improved vertical photo-detector cells may be arranged as a group that defines a sensor cell.
In yet another example of the present invention, an imaging sensor is arranged as an array of pixel cells. The imaging sensor includes a first, second, third, and fourth sensor. The first sensor is sensitive to light that approximately corresponds to a first wavelength. The first sensor is centered about a first pixel location in the array. The second sensor is sensitive to light that approximately corresponds a second wavelength. The second sensor is centered about a second pixel location in the array. The third sensor is sensitive to light that approximately corresponds a third wavelength. The third sensor is centered about a third pixel location in the array. The fourth sensor that is sensitive to light that approximately corresponds the third wavelength. The fourth sensor is centered about a fourth pixel location in the array. A sensor material is associated with a selected one of the first, second, third, and fourth sensors. The sensor material includes a central portion and an extending portion. The central portion is located within an improved vertical photo-detector cell. The extending portion is located within another improved vertical photo-detector cell that is adjacent to the improved photo-detector cell. The central portion is coupled to the extending portion such that photo-carriers are collected from the adjacent improved vertical photo-detector cell to increase sensitivity of the selected sensor.
According to a further aspect of the present invention, the array of pixel cells includes a set of first, second, third, and fourth alternating patterns. The first alternating pattern of first and third sensors extends from a pixel cell along a first direction. The second alternating pattern of first and fourth sensors extends from the pixel cell along a second direction. The third alternating pattern of second and third sensors extends from the pixel cell along the first direction. The fourth alternating pattern of second and fourth sensors extends from the pixel cell along the second direction.
According to yet a further aspect of the present invention, the selected one of the sensors is configured in a shaped pattern that is defined by the central and extending portions of the sensor material. The shaped pattern may correspond to a quadrilateral that is substantially centered about a pixel in the array. The shaped pattern may be oriented at angle of forty-five degrees about a pixel in the array. The shaped pattern may provide a resulting sensor that has a fill-factor of approximately 100% for a color associated with the first wavelength. The shaped pattern may have extending portions of sensor material that extend along an orthogonal set of axis with respect to the center of sensor material. The sensor material associated with selected one of the sensors may have an effective area that is substantially three times the area associated with a pixel in the array.
According to still a further aspect of the present invention, a group of sensors may outline a central region that includes a fifth sensor that is sensitive to light that approximately corresponds to the second wavelength. The fifth sensor is configured to drain photo-carriers that are induced by second wavelength related light that is incident on the central region.
In still another example, an imaging sensor includes a first, second, and third means for collecting photo-carriers. The first means for collecting photo-carriers is configured to collect first photo-carriers from a first improved vertical photo-detector cell. The first photo-carriers are associated with a first color. The second means for collecting photo-carriers is configured to collect second photo-carriers from a second improved vertical photo-detector cell that is located adjacent the first improved vertical photo-detector cell. The second photo-carriers are associated with a second color. The third means for collecting photo-carriers is configured to collect first photo-carriers from the second improved vertical photo-detector cell. A means for coupling is configured to couple the first photo-carriers that are collected from the second means for collecting photo-carriers to the first photo-carriers that are collected from the first means for collecting photo-carriers such that photo-carriers that are associated with the first color from the improved vertical photo-detector cell and the adjacent improved vertical photo-detector cell are combined to increase sensitivity to the first color in the sensor.
A more complete appreciation of the present invention and its improvements can be obtained by reference to the accompanying drawings, which are briefly summarized below, the following detail description of presently preferred embodiments of the invention, and the appended claims.